The third calmodulin family protein in Tetrahymena. Cloning of the cDNA for Tetrahymena calcium-binding protein of 23 kDa (TCBP-23).
Recently, we proved the existence of the second calmodulin family protein in Tetrahymena (Tetrahymena calcium-binding protein of 25 kDa, TCBP-25) by analyzing its cDNA (Takemasa, T., Ohnishi, K., Kobayashi, T., Takagi, T., Konishi, K., and Watanabe, Y. (1989) J. Biol. Chem. 264, 19293-19301). During the amino acid sequence determination of TCBP-25, we became aware of the fact that another polypeptide carrying calcium-binding domains of EF-hand type existed in addition to Tetrahymena calmodulin and TCBP-25. This third calmodulin family protein from Tetrahymena was confirmed by isolating its cDNA clones. One of the cloned cDNAs contains 763 nucleotides and encodes a protein that is composed of 207 amino acid residues and has a molecular mass of 23,413 daltons. This predicted protein possesses four EF-hand type calcium-binding domains, so we have designated it as Tetrahymena calcium-binding protein of 23 kDa (TCBP-23). TCBP-23 is similar (35% homology) but clearly different from TCBP-25. The TCBP-23 gene is actively transcribed in vivo as a 0.84-kilobase RNA. Thus, it follows that Tetrahymena cells have three different calmodulin family proteins: calmodulin, TCBP-25 and TCBP-23. These proteins are expected to provide important clues for solving the mechanisms of calcium-dependent phenomena, such as ciliary reversal.
Takemasa
T
T
Institute of Biological Sciences, University of Tsukuba, Ibaraki, Japan.
Takagi
T
T
Kobayashi
T
T
Konishi
K
K
Watanabe
Y
Y
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002135:Calcium-Binding Proteins / Q000235:genetics*; D002147:Calmodulin / Q000235:genetics*; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics*; D015723:Gene Library; D007256:Information Systems; D008969:Molecular Sequence Data; D008970:Molecular Weight; D015345:Oligonucleotide Probes; D010449:Peptide Mapping; D011487:Protein Conformation; D013768:Tetrahymena / Q000235:genetics*
D002135:Calcium-Binding Proteins; D002147:Calmodulin; D015345:Oligonucleotide Probes; D004247:DNA